Portable, collapsible chairs that can be rolled up for easy storage and transport are well known. Chairs of this type are shown, for example, in U.S. Pat. Nos. 6,164,726 to Reeves et al., 6,755,462 to Zheng, and 6,382,715 to Tang.
A conventional collapsible chair comprises a foldable chair frame constructed by metal tubes and a seat fabric. The foldable chair frame comprises a plurality of construction tubes to construct a back frame and a seat frame for supporting the fabric seat. The fabric seat of the conventional collapsible chair is preferably made of durable fabric, such as twilled nylon or other mixing material such as polyurethane.
Because conventional collapsible chairs can be quickly and easily unfolded for use and folded into a compact fold-up structure for transport, the user can carry the collapsible chairs to all kinds of outdoor activities, such as camping and sporting events. However, conventional collapsible chairs are not ideal for winter use because the nylon material of the fabric seats does not accumulate heat so that the user has to tolerate the cold air on his backside. Even though the body temperature of the user may warm up the upper contacting surface of the fabric seat, the bottom surface immediately wicks away the body heat to the cold environment below.
Folding stadium seats are also well known, and some even incorporate a heating element for warming the user's back and seat. For example, U.S. Pat. Nos. 6,007,572 to Baldwin and 6,848,746 to Gentry disclose folding stadium seats with heating elements. However, these types of seats are uncomfortable and are typically used on the bench seating typical of sports stadiums. Folding stadium seats are not practical or comfortable for use while camping or watching outdoor events where no stadium seating is provided.
What is needed is a stand-alone, collapsible, portable chair that warms the user's body and is comfortable and easy to transport.